Paper shredders of the above-described type have the advantage over paper shredders without a cut-off delay, that when the paper clears the sensor, the shredding means or communicator continues to operate so that residual portions of the paper will not remain readable. In paper shredders without such a shut-off retarder, immediately upon clearing the sensor, the communicator is cut off, thereby leaving a portion of the paper to be comminuted so that it can be read.
In the past, the apparatus has utilized electronic means, such as a time-delay switch which remains in the closed state even after the sensor has been cleared by the trailing edge of the paper to ensure that the paper will be comminuted up to the trailing edge. The problem with such systems is that delayed-opening switches and time-delay circuitry are expensive, are not always reliable and require relatively frequent maintenance and replacement.